This invention relates to an apparatus for inserting coils and wedges into stator cores of dynamoelectric machines. In particular, this application relates to an apparatus for insertion of coils and wedges into lengthy stator cores, namely stator cores which have a relatively large stack height to bore diameter ratio.
A number of machines have been developed for inserting pre-wound coils and wedges into stator cores. In such machines the coils are generally formed on winding machines and are placed over an array of tooling blades or fingers for subsequent insertion into a stator core. Insulating wedges may be inserted by the same equipment to separate windings from one another or to insulate the windings from the stator core.
In such machines, the wedge guides for guiding the wedges into the stator slots are arranged in a circular array and are supported by a housing. A moveable blade pack including a stripper and an array of blades is disposed inside of the wedge guide array. After the coils have been draped over the blades, a blade and core alignment device is loaded onto the array of blades. The core is then loaded onto the alignment device and onto the array of blades until the core come into contact with the array of wedge guides. The core is secured in place with clamp arms and the blades are inserted into the bore of a stator core for insertion of the pre-wound coils into the stator core slots by means of relative axial movement of the stripper with respect to the blade array. During the insertion of the coils into the stator core, the wedges are also inserted into the slots of the stator core. During such wedge insertion, the wedges are guided by the wedge guides and supported by the stripper.
In the insertion of pre-wound coils into lengthy cores, the blades will need to travel a substantial axial distance and therefore may move completely out of the wedge guide array. Since the wedge guides are generally made of fairly thin metal, when the coil wire end turns are pulled tight during insertion, the wedge guides will be deflected radially and axially inward toward the center of the circular wedge guide array once the blades have left the wedge guide array and therefore no longer support the wedge guides. Accordingly the wedge track formed by and located between the individual wedge guides through which the wedges are pushed into the slots of the stator core will no longer align accurately with the stator when the wedge guides are thus deflected. The stator core iron may therefore dig into the wedge and may even stop the wedge from further movement. Accordingly less than complete insertion of the wedges may be encountered during such wedge insertion operations. If the deflection of the wedge guides is great enough, it is even possible that the entire coil insertion process may be stopped because of jamming of the apparatus.
An additional problem that occurs in such insertion operations is that the blade pack, consisting of the blades, the stripper and the blade holder, upon its retraction back into the wedge guide array, would interfere mechanically with the deflected wedge guides, therefore potentially causing severe wear of both the wedge guides and the blades. After a sufficient number of insertion cycles, the wear of both the wedge guides and the blades may be so extensive that they need to be replaced. Such replacement is relatively expensive because of the cost of providing accurately machined wedge guides as well as insertion blades.
Thus it is desired to provide an apparatus wherein the wedge guides are supported against radial inward deflection by the coils throughout the insertion process both in cases of standard length stator cores and very long stator cores. Such support would avoid or reduce the problems enumerated above.